Automatic machine for grinding and polishing a surface of masonry



`July 3, 1962 AKIO SHIMIZU AUTOMATIC MACHINE FOR GRINDING AND POLISHING A SURFACE OF MASONRY Filed Aug. l, 1960 Rea United States Patent O 3,041,793 AUTOMATIC MACHINE FOR GRINDING AND POLISHENG A SURFACE F MASONRY Akio Shimizu, Minamigata, Gebe-cho, Anpachi-gnn, Gifu-ken, Japan Filed Aug. 1, 1960, Ser. No. 46,497 2 Claims. (Cl. 51-1S0) The present invention relates to an automatic grinder suitable for polishing a surface of masonry of marble, granite, articial stones, tile and the like.

It has been known to polish the surface of stones such as marble, granite, artiiicial stones, tiles and the like by employing a grinding machine which has a grinding member which rotates around its axis while it is maintained in contact with a surface to be worked. In such a grinding machine, if the grinding member can be moved axially while it is rotated around its axis and the pressure applied to said member can be adjusted in order to keep the member pressed against the surface to be worked with a constant force irrespective of the roughness of the surface to be worked, good results will be obtained and the wear and tear on the grinding member will be lessened.

Furthermore, since even if the grinding member is worn, it can be advanced to contact the surface with constant pressure so that the grinding member can be used for a long time with no necessity of replacing it.

An object of the present invention is to provide such a grinding machine which has relatively simple construction and can satisfactorily achieve the functions described above.

Another object of this invention is to provide a grinding machine as described above which has means for supplying automatically a liquid such as water, oil and the like to the processed surface to improve the nished surface and to lessen the wear and tear on the grinding member.

The above described features and advantages as Well as other features and advantages will be understood clearly from the following detailed explanation reference being made to the accompanying drawings in which:

FIG. 1 is a schematic side view partly in section illustrating one grinding machine provided according to the present invention; and

FIG. 2 is a similar schematic view illustrating another embodiment of the present invention.

In FIG. 1, a hollow cylinder 1 having a cylinder head 3 fixed at one end and a xed pulley 2 in the middle is rotatably mounted on a frame S by means of bearings 4 and 4. A piston 6 fixed at the end of a rod 7 is slidably y movable in this cylinder and said rod has a fixed grinding member 8 at the other end. The cylinder 1 is rotated by a driving motor M1 through the intermediary of the pulley 2. The cylinder head 3 has a key 10 and the rod 7 is provided with a key groove '9 in engagement with said key 10. Consequently, when the cylinder 1 is rotated, the rod 7 is also rotated together with the fixed grinding member 8.

Into the chamber within the cylinder, a pressure fluid is supplied from a pump and motor M2 through pipes 1S and 12. ln the drawing, 13 represents a packing which provides fluid tightness between the pipe 12 and the cylinder 1. When fluid is introduced to the left side of the piston 6, the piston is pushed to the right against the force of a spring 11 inserted between the piston 6 and the cylinder head 3 and thus the grinding member 8 fixed at the end of the rod 7 is pressed against the surface S confronting the grinding member.

It is one of the important features of the present invention to press the grinding member 8 with substantially constant force against the surface to be worked. For this purpose, a pressure meter 21 and a switch 22 controlled by said pressure meter 21 are provided and it is so arranged that when the pressure in the cylinder reaches a certain value the switch 22 is operated to stop the motor M2 supplying fluid into the cyinder 1. For the maintenance of the pressing force, the device described above is not sufficient alone, since the surface S of the stone work is irregular and protrudes in some parts and is recessed in others. When the grinding member 8 is against the protruding part, the piston 6 is moved to the right to increase the pressure in the left chamber of the cylinder 1.

In order to overcome such an increase, the apparatus of the present invention is provided with an automatic pressure adjuster 16 affixed to the pipe 12. This adjuster 16 comprises a valve 24 which is normally closed by the action of a spring 2S. When the pressure in the cylinder and consequently that in the pipe 12 is increased due to a protrusion on the surface S, the valve 24 is opened against the force of the spring to allow the iiuid from the pipe 12 to move into a discharge pipe 19 and thus the pressure in the cylinder 1 is lowered to a predetermined value and the valve 24 is again closed by the action of the spring 25. When the grinding member 8 confronts a recessed part of the surface S, the pressure in the cylinder 1 is lowered and the mete-r 21 operates the switch 22 to drive motor M2 to introduce fluid into the cylinder. Accordingly, even if the surface S is irregular, the grinding member 8 can be pressed against the surface with substantially constant pressing force. In the drawing, 17 represents a two-way cock which connects the pipe 12 selectively to the introduction pipe 18 or the discharge pipe 19, and 20 is a handle for operating the cock 17 The operation of this machine is as follows. When it is desired to begin a grinding operation, the handle 20 is operated to connect the pipe 18 to the pipe 12. It iS arranged so that this operation of the handle 20 also starts the driving pump motor M2 for supplying ilnid into the cylinder through pipes 18 and 12. When the pressure in the cylinder 1 reaches a predetermined value, the pressure meter 21 operates the switch 22 to stop the supply of fluid into the cylinder 1.

In the meantime, the rotation of the cyinder 1 and consequently the rotation of the rod 7 and the grinding member 8 is started lby motor M1 adapted to rotate the pulley 2. Accordingly when the machine is applied onto a surface S, 'the grinding action on the surface is effected. During this action, the pressure adjuster 16 and the meter 21 associated with the switch 22 operate automatically to maintain the pressure in the cylinder practically constant and therefore satisfactory Working can be attained with little wear and tear of the grinding member 8. When the work is completed, the pipe 12 is connected yto the discharge pipe 19 by operating the cock 17 by the handle 2t). Under this condition, the piston 6 is moved to the left under the action of the spring 11 and fluid in the left chamber of the cylinder is discharged through the pipe 12 -into the discharge pipe 19. Said operation of the handle 20 may be connected to a means which acts to stop the motor M1 for driving the pulley 2 and also to stop the motor M2 for driving the pump for the introduction of uid into the cylinder 1. In this specification, a description of such means is omitted since it is easily provided by those skilled in the art.

In a grinding operation, it is often desirable to have a. fluid such as water, oil and other suitable liquids on the surface under working for increasing workability of the surface and the prevention of excessively high temperal ture and so forth.

The operation of this cock 23 may also be associated with the operation of the handle 2t) so that the supply of the fluid to the surface Sis always effected when this grinding machine is operated.

The embodiment of FIG. 2 is `substantially the same as that of FIG. 1 excepting that the cylinder 26 is not rotated and the rod 31 of the piston 30 is rotated.

As illustrated in the drawing, a cylinder 26 has fianges 27 and 28 on opposite ends and is ixed on a frame 29 by said flanges. A piston 30 rotatably mounted on a rod 31 by means of bearings 32 and 33 is slidable in the cylinder 26 in the axial direction together with the rod 31. The rod 31 is rotatably supported on the frame by means of a bearing 34 and has a grinding member 35' at the end opposite to the piston 30. The rod 31 has a key groove 36 which is in engagement with a key 38 of a pulley 37 rotatably mounted on the frame 29.

When the pulley 37 is rotated by a motor M3 the rod 31 is also rotated to rotate the grinding member 35, but when fluid is introduced into the right chamber of the cylinder 26, it can be moved axially to the left together with the piston 30 and the grinding member 35. A pipe 39 is connected to the right end of the cylinder 26 for the introduction and discharge of uid. In the drawing, 21 is a pressure meter, 22 a switch for the operation of a motor M4 for the introduction of fluid via pipe 18 into the cylinder, 19 a discharge pipe, 16 a pressure adjuster, 17 a two-way cock, and a handle respectively, and their constructions and functions are same as the corresponding par-ts of FIG. l.

By the operation of the handle 20, fluid is introduced into the cylinder 26 through the pipe 18, the cock 17, the pipes 40 and 39 to move the piston 30 and consequently the grinding member 35 against a surface S with substantially constant pressure by virtue of the pressure adjuster 16 and also the meter 21 and the switch 22. When the cock 17 is operated to connect the pipe 40 to the discharge pipe 19, the piston is moved to the right under the action of a spring r4-2 inserted between the piston 30 and the left end of the cylinder 26. During the working operation, the pulley 37 is rotated by motor M3 to rotate the rod 31 and the grinding member 35. 40 represents a casing covering the grinding member and a pipe 41 is provided to supply a desired liquid such as water and oil inside said casing 140. Thus any 4desired liquid may be supplied between the grinding member 35 and the surface S to be Worked.

The apparatus of FIG. 2 has less parts where leakage of iluid may take place and is more compact in comparison with that of FIG. 1, and therefore it is more suitable when the available space for the installation is narrow.

The grinding operation of the apparatus of the present invention can be operated very smoothly to give very satisfactory results due to the presence of the automatically operated switch 22 and pressure adjuster 16.

When it is desired to polish wide Walls of marble, granite, tiles and the like, this can be achieved easily by moving the grinding machine with no necessity of removing the stones or tiles from the wall in a relatively short time to restore the beautiful appearance of new buildings. This grinding machine can be applied conveniently even to a surface which has irregularities with no fear of breaking the machine through the excessive stress which may be caused if excessive pressure is caused in the cylinder and other constituent elements. The Working may be carried out uniformly Without leaving unpolished spots on the surface. Moreover when a liquid is supplied to the surface under working, this can `also be attained automatically with no troublesome operations to obtain an excellent finished surface and to avoid excessive Wear and tear on the grinding member.

What is claimed is:

1. An automatic machine for grinding and polishing a masonry surface, said machine comprising a cylinder, a piston slidably mounted in the cylinder, a rod coupled to said piston and defining an axis, said rod being coupled to said cylinder and being rotatable on said axis in response to rotation of the cylinder, said rod being movable in axial direction together with said piston, a grinding member on said rod, means for rotating the rod, means for introducing a pressure medium into the cylinder to move the piston and thereby said rod, pressure responsive means coupled to the cylinder and coupled Vto `and adapted to control the means for introducing fluid into the cylinder when pressure in the cylinder varies with respect to a predetermined value, and a pressure adjuster means coupled to said cylinder and comprising a valve which is adapted to be opened when the pressure in the cylinder is above a predetermined value to allow the discharge of said medium from the cylinder, said grinding member being adapted for being rotated and applied to said surface under substantially constant pressure irrespective of irregularities in the surface.

2. A machine according to claim l comprising means for supplying a iluid through said rod to said surface.

References Cited in the tile of this patent UNITED STATES PATENTS 1,871,042 Cavicchi Aug. 9, 1932 2,358,269 Wemhoner Sept. 12, 1944 2,836,996 Bissey June 3, 1958 2,906,066 Laverdisse Sept. 29, 1959 

